In this month’s troubleshooting situation, the equipment is a four-ton heat pump, and the customer’s complaint is that the unit is blowing cool air.

When you arrive, you confirm that the thermostat is properly set for the heating mode, and that the indoor air handler is operating with normal airflow.

As your next step, you check the outdoor unit and find that the compressor and outdoor fan motor are not operating. Consulting the wiring diagram shown in Figure One, your first electrical check at the L1 and L2 connections of the contactor shows 230 VAC.

Your next electrical checks are:

  1. At the contactor coil: Result = 24 VAC.
  2. At T1 and T2 of the contactor: Result = 0 VAC.

Your troubleshooting question: What is the next step you need to take in servicing this equipment?

Let us know your answer here!